Devices for treating a part of a body, for example by cutting hair on a part of a body to be treated, include powered hand-held devices that are placed against a part of a user's body and moved over areas where hair is to be cut, for example a trimmer. Such devices include mechanical hair cutting devices. The user selects a cutting length by adjusting or selecting a guide, such as a comb, which extends over a cutting blade and then selects which areas of hair to cut and which areas should not be cut by positioning and moving the device appropriately.
When cutting a user's own hair, or someone else's hair, significant skill is required to create a particular hairstyle or to provide a presentable result. Furthermore, it is difficult to repeat the haircut, or to copy a haircut. Although it is possible to use a trimmer to cut hair, such a device generally provides for cutting hair to a consistent length across the head. Such devices are difficult to accurately position on a user's head, for example. The accuracy of the treatment provided by the device depends on the user's skill and steady hand. Moreover, the device and the user's hand and arm may impede the user's view thereby making it difficult to position and move the device accurately.